1. Field of Invention
This invention relates to a brake-actuating mechanism for a drum brake device, designed to mechanically move a pair of brake shoes away from each other in response to operation of a brake lever. More particularly, it relates to a brake cable connecting apparatus designed to prevent an inadvertent disconnection of a brake cable from the brake lever, even during the transportation of the drum brake device with the brake cable already connected to the brake lever of the brake-actuating mechanism and to independently disconnect the brake cable from the brake lever without disassembling any associated part.
2. Description of the Related Art
One conventional brake cable connecting apparatus in a brake-actuating mechanism, as described above, is illustrated in FIGS. 14 and 15, and is disclosed in the Japanese Provisional Patent Publication No. 2000-108855. In the figures, a strut, a brake lever and a brake cable are identified by reference numerals 1, 2 and 3 respectively. The strut 1 and the brake lever 2 define a brake-actuating mechanism. The strut 1 has a notched groove 1a at one end thereof, with which one brake shoe (not shown in the figures) engages. The brake lever 2 is pivotally attached to the other end of the strut 1 at a proximal end thereof with a pivot pin 4 and has a notched groove 2a at the proximal end thereof adjacent to the pivot pin 4, with which the other brake shoe (not shown in the figures) engages. Cable end engagement grooves 2b are formed on a pair of free ends of the brake lever 2, with which a cable end 3a of the brake cable 3 engages in the cable operating direction as shown in FIG. 15.
In the above construction, if a cable operating force as shown in the direction of arrow xe2x80x9cWxe2x80x9d is applied to the brake lever 2 via the brake cable 3, the brake lever 2 rotates around the pivot pin 4 in a corresponding direction, thereby pushing the associated brake shoe (not shown in the figures) leftward.
At the same time, such pivotal movement of the brake lever 2 around the pivot pin 4, as described above, furnishes the strut 1 with a counteracting force via the pivot pin 4, thereby pushing the strut 1 together with the associated brake shoe (not shown in the figures) rightward.
Due to the movement of both brake shoes moving away from each other, the brake shoes are pushed against an inner circumferential surface of a brake drum (not shown in the figure), thereby providing a predetermined braking action.
When the cable end 3a of the brake cable 3 first engages with the engagement grooves 2b on the free ends of the brake lever 2, the cable end 3a is temporarily positioned above the engagement grooves 2b according to a process as shown in FIG. 14 and then passes through a slightly narrow clearance in the brake lever 2, thereby snapping the cable end 3a in the engagement groove 2b according to a process as shown in FIG. 15.
In this type of drum brake device, for the purpose of inspecting or exchanging the brake cable while the drum brake device is being mounted on a vehicle, the brake cable already connected to the brake lever needs to be disconnected.
However, in the above-described conventional drum brake device, disconnection of the brake cable is exceedingly difficult. In order to disconnect the brake cable, it is necessary to dismount the brake drum and to disassemble the drum brake device and the brake-actuating mechanism. Accordingly, it is difficult to prevent either of or both the inadvertent disconnection of the brake cable from the brake lever while transporting the drum brake device with the brake cable and the disconnection of the brake cable independently from the brake lever under the condition where the brake drum and the drum brake device are already mounted on the vehicle.
An object of a first embodiment of the invention is to provide the brake cable connecting apparatus preventing the inadvertent disconnection of the brake cable from the brake lever while transporting the drum brake with the brake cable and the disconnection of the brake cable independently from the brake lever without dismounting of the brake drum and disassembling the drum brake device and the brake-actuating mechanism.
An object of a second embodiment of the invention is to provide the brake cable connecting apparatus achieving the same level of effectiveness as in the first invention by way of allocating a groove on the brake lever for supporting the top of the tool which pushes the brake lever.
An object of a third embodiment of the invention is to provide the brake cable connecting apparatus achieving the same level of effectiveness as in the first invention by way of allocating a notch on the brake lever for guiding the top of the tool which pushes the brake lever.
In a brake actuating mechanism comprising a brake lever and a strut, that rotate relatively around their pivotally attached section in order to move the brake shoes away from each other when the cable operating force of the brake cable is transmitted to the brake lever via the cable end, on the occasion of engaging the cable end with the free end of the brake lever, the brake cable is lightly pulled in the cable operating direction against a springing force of a return spring, thereby engaging the cable end with the free end of the brake lever. If the cable end needs to be disengaged from the brake lever, the above process of engaging the cable end is reversed, i.e., the brake cable is pushed in the cable releasing direction and at the same time the brake lever and the strut relatively rotate around their pivotally attached section to move the brake shoes away from each other so as to allow movement of the cable end.
In the first embodiment of the invention, upon slightly pulling the brake cable in the cable operating direction against a springing force of a return spring, the free end of the brake lever is displaced to form a space allowing the cable end to pass and to be positioned on the free end of the brake lever; then the contracting force of the return spring brings the free end of the brake lever back to the initial position, thereby preventing the inadvertent disengagement of the cable end.
The first embodiment of the invention also has a guide section for supporting a top of a tool, formed on a surface of the brake lever at a side of the cable releasing direction, to press the brake lever in the cable operating direction by applying an external force by a tool, such as a screw driver, from outside of the brake to cause the relative rotation of the brake lever and the strut around their pivotally attached sections.
Accordingly, the inadvertent disengagement of the cable end from the brake lever while transporting the drum brake device with the brake cable is prevented, thereby eliminating the possibility of misassembling the drum brake device when mounting on a vehicle and also reducing the time for assembly because it is not necessary to reassemble the cable end.
If the brake cable is disconnected for an exchange, neither dismounting the brake drum nor disassembling the components in the brake device is necessary thereby facilitating the process of and reducing the time for the disconnection of the brake cable. The second embodiment of the invention has a groove in the free end of the brake lever to be used as a guide section for accurately supporting a top of a tool and easily pressing the brake lever, which makes this process more accurate and safer, and therefore it achieves the same level of effectiveness as in the first embodiment of the invention more effectively. The third embodiment of the invention has a notch in the free end of the brake lever as a guide section for accurately supporting a top of a tool and easily pressing the brake lever, which makes this process more accurate and safer, and therefore it achieves the same level of effectiveness as in the first embodiment of the invention more effectively.